216 Kleopatra

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216 Kleopatra
Kleopatra.jpg
3D model of Kleopatra from radar observation (animation)
Discovery [1]
Discovered by J. Palisa
Discovery site Pola Obs.
Discovery date 10 April 1880
Designations
MPC designation (216) Kleopatra
Pronunciation (/ˌkliːəˈpætrə, -ˈpɑː-, -ˈpeɪ-/[6])
Named after
 Cleopatra (Egyptian queen)[2]
A905 OA · A910 RA
main-belt [1][3] · (central) [4]
background [5]
Orbital characteristics [3]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc 137.60 yr (50,259 d)
Aphelion 3.4951 AU
Perihelion 2.0931 AU
2.7941 AU
Eccentricity 0.2509
4.67 yr (1,706 d)
346.24°
0° 12m 39.6s / day
Inclination 13.113°
215.36°
180.11°
Known satellites 2 (Alexhelios · Cleoselene)
Physical characteristics
Dimensions 217 km × 94 km × 81 km[7]
Mean diameter
 102.93±3.81 km[8]
104.3 km[9]
121.55±1.60 km[10]
124 km[3]
135.07±2.1 km[11]
137.794 km[4][12]
138.000±19.37 km[13]
Mass (4.64±0.02)×1018 kg[14]
Mean density
 4.27±0.86 g/cm3[15]
5.394 h[16][17]
5.386 h[18]
5.385 h[19]
5.38527 h[20]
5.399 h[21]
5.38528 h[22][23][24][25]
5.385263 h[26]
5.38529 h[27]
5.385277 h[28]
5.386±0.003 h[29]
5.376±0.006 h[30]
5.379±0.002 h[31]
5.38±0.05 h[30]
5.3848±0.0003 h[30]
5.386±0.001 h[4][32]
5.39±0.05 h[30]
5.41±0.05 h[33]
5.385414±0.000006 h[30]
0.1164±0.004[11]
0.170[9]
0.149±0.005[10]
0.1111±0.0336[13]
0.1068[12]
0.200±0.028[8]
M (Tholen)[3] · Xe (SMASS)[3]
M [13][34]
B–V = 0.713[3]
U–B = 0.238[3]
7.30[3][8][11][10][13]
7.35±0.02[4][12][35] · 7.45[9]

216 Kleopatra (/ˌkliːəˈpætrə, -ˈpɑː-, -ˈpeɪ-/) is a metallic, ham-bone-shaped asteroid and trinary system orbiting in the central region of the asteroid belt, approximately 138 kilometers (86 miles) in diameter. It was discovered on 10 April 1880, by Austrian astronomer Johann Palisa at the Austrian Naval Pola Observatory, in what is now Pula, Croatia.[1] The M-type asteroid has a shorter than average rotation period of 5.4 hours.[4] It was named after Cleopatra, the famous Egyptian queen. Two small minor-planet moons were discovered in 2008, and later named Alexhelios and Cleoselene.

Orbit and classification[edit]

Kleopatra is a non-family asteroid from the main belt's background population.[5] It orbits the Sun in the central asteroid belt at a distance of 2.1–3.5 AU once every 4 years and 8 months (1,706 days; semi-major axis of 2.79 AU). Its orbit has an eccentricity of 0.25 and an inclination of 13° with respect to the ecliptic.[3] The body's observation arc begins at Leipzig Observatory (534) on 20 April 1880, ten days after to its official discovery observation at Pola Observatory.[1]

Physical characteristics[edit]

Kleopatra is a relatively large asteroid, measuring 217 × 94 × 81 km.[7] Calculations from its radar albedo and the orbits of its moons show it to be a rubble pile, a loose amalgam of metal, rock, and 30–50% empty space by volume, likely due to a disruptive impact prior to the impact that created its moons.

Kleopatra has an unusual shape. Initial observations with the ESO 3.6 m Telescope at La Silla, run by the European Southern Observatory, were interpreted to show a double source with two distinct lobes of similar size.[36] These results were disputed when radar observations at the Arecibo Observatory showed that the two lobes of the asteroid are connected, resembling the shape of a ham-bone. The radar observations provided a detailed shape model that appeared on the cover of Science Magazine.[7]

Moons[edit]

In 1988 a search for satellites or dust orbiting this asteroid was performed using the UH88 telescope at the Mauna Kea Observatories, but the effort came up empty.[37] In September 2008, Franck Marchis and his collaborators announced that by using the Keck Observatory's adaptive optics system, they had discovered two moons orbiting Kleopatra.[38] The outer and inner satellites are about 8.9 ± 1.6 and 6.9 ± 1.6 km in diameter, with periods of 2.32 ± 0.02 and 1.24 ± 0.02 days, respectively.[39][40]

In February 2011, the minor-planet moons were named Alexhelios (/ˌælɪksˈhiːlioʊs/, outer) and Cleoselene (/ˌkliːoʊsɪˈliːniː/, inner), after Cleopatra's children Alexander Helios and Cleopatra Selene II.[1]

Origin[edit]

It is believed that Kleopatra's shape, rotation, and moons are due to an oblique impact perhaps 100 million years ago. The increased rotation would have elongated the asteroid and caused Alexhelios to split off. Cleoselene may have split off later, around 10 million years ago. Kleopatra is a contact binary – if it were spinning much faster, the two lobes would separate from each other, making a true binary system.[14]

References[edit]

  1. ^ a b c d e "216 Kleopatra". Minor Planet Center. Retrieved 22 April 2017.
  2. ^ Schmadel, Lutz D. (2007). "(216) Kleopatra". Dictionary of Minor Planet Names – (216) Kleopatra. Springer Berlin Heidelberg. p. 34. doi:10.1007/978-3-540-29925-7_217. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f g h i "JPL Small-Body Database Browser: 216 Kleopatra" (2016-09-20 last obs.). Jet Propulsion Laboratory. Retrieved 22 April 2017.
  4. ^ a b c d e "LCDB Data for (216) Kleopatra". Asteroid Lightcurve Database (LCDB). Retrieved 22 April 2017.
  5. ^ a b "Small Bodies Data Ferret". Nesvorny HCM Asteroid Families V3.0. Retrieved 19 October 2017.
  6. ^ "Kleopatra". Dictionary.com Unabridged. Random House. Retrieved 2016-01-23.
  7. ^ a b c Ostro, Steven J.; Hudson, R. Scott; Nolan, Michael C.; Margot, Jean-Luc; Scheeres, Daniel J.; Campbell, Donald B.; et al. (May 2000). "Radar Observations of Asteroid 216 Kleopatra". Science. 288 (5467): 836–839. Bibcode:2000Sci...288..836O. doi:10.1126/science.288.5467.836. Retrieved 21 March 2018.
  8. ^ a b c Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 22 April 2017.
  9. ^ a b c Shevchenko, Vasilij G.; Tedesco, Edward F. (September 2006). "Asteroid albedos deduced from stellar occultations". Icarus. 184 (1): 211–220. Bibcode:2006Icar..184..211S. doi:10.1016/j.icarus.2006.04.006. Retrieved 22 April 2017.
  10. ^ a b c Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 22 April 2017.
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  15. ^ Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73: 98–118, arXiv:1203.4336 [astro-ph.EP], Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009 Cite uses deprecated parameter |class= (help) See Table 1.
  16. ^ Scaltriti, F.; Zappala, V. (May 1978). "Photoelectric photometry of asteroids 37, 80, 97, 216, 270, 313, and 471". Icarus. 34 (2): 428–435. Bibcode:1978Icar...34..428S. doi:10.1016/0019-1035(78)90178-1. Retrieved 22 April 2017.
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  18. ^ Kennedy, H. D.; Tholen, D. J. (December 1981). "The brightness variations of asteroid 216 Kleopatra". Astronomical Society of Australia. 4: 414–417. Bibcode:1982PASAu...4..414K. ISSN 0066-9997. Retrieved 22 April 2017.
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External links[edit]

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